Field of the Invention
The present invention relates to an ophthalmic lens such as a contact lens and an intraocular lens.
Description of Related Art
Various properties are required for an ophthalmic lens such as a contact lens and an intraocular lens. For instance, the contact lens which is worn on a sensitive cornea of the eye is intrinsically required to give excellent wearing comfort, so that the wearer is less likely to feel the contact lens as a foreign object. On the other hand, in recent years, development of a novel intraocular lens formed of a lens material (polymer) having excellent flexibility has been desired, since the intraocular lens formed of such a highly flexible lens material (polymer) can be folded into a small piece, and inserted into the eye through a small incision.
Further, in recent years, the contact lens, in particular, is required to exhibit more excellent oxygen permeability than that of the conventional contact lens, so that a sufficient amount of oxygen is supplied to the cornea.
For instance, it is widely known that a silicone polymer having a siloxane main chain including a siloxane unit as a repeating unit has excellent flexibility and excellent oxygen permeability. The silicone polymer has been used as a material of various kinds of ophthalmic lens including the contact lens. For instance, a copolymer (silicone hydrogel) of a polysiloxane-based macromonomer in which a polymerizable group is bonded to the siloxane main chain, and a hydrophilic monomer such as N-vinylpyrrolidone and dimethyl acrylamide gives a highly oxygen-permeable water-absorptive lens. Accordingly, various studies have been made and various techniques have been proposed regarding the ophthalmic lens (particularly, contact lens) formed of the silicone hydrogel, and a method of production of such an ophthalmic lens. Specifically, a silicone hydrogel contact lens is proposed in JP-T-2008-511870, an ophthalmic lens for long-term wearing is proposed in JP-A-2010-20330 and a method of production of a silicone hydrogel contact lens is proposed in JP-T-2012-513042.
However, it cannot be said that the conventional polysiloxane-based macromonomer such as those described in the above-indicated Patent Documents 1 to 3 exhibits sufficiently high compatibility with a hydrophilic monomer. Therefore, in production of the ophthalmic lens using the conventional polysiloxane-based macromonomer, and the hydrophilic monomer or the like, there is a risk that when the components are mixed together, the mixture is clouded or whitened, or a polymer obtained by polymerization is clouded or whitened, depending on a combination of the components, giving rise to a problem that the combination of the components is limited in order to obtain a transparent ophthalmic lens.
On the other hand, as for the intraocular lens, there is a problem of so-called glistening, which is a phenomenon in which white spots appear within the intraocular lens when it is implanted in the eye and hydrated, and transparency of the intraocular lens is considerably lowered or lost. Under the above-described circumstances, Patent Document 4 (Japanese Patent No. 3641110) proposes an intraocular lens formed by copolymerization of a plurality of monomer components having excellent compatibility with each other, to restrict occurrence of the glistening.